Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon. The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size, which allow more components to be integrated into a given area.
As semiconductor technologies further advance, stacked semiconductor devices have emerged as an effective alternative to further reduce the physical size of a semiconductor device. In a stacked semiconductor device, active circuits such as logic, memory, processor circuits and the like are fabricated on different semiconductor wafers. Two or more semiconductor wafers may be installed on top of one another to further reduce the form factor of the semiconductor device.
Two semiconductor wafers may be bonded together through suitable bonding techniques. Some commonly used bonding techniques for semiconductor wafers include direct bonding, chemically activated bonding, plasma activated bonding, anodic bonding, eutectic bonding, glass frit bonding, adhesive bonding, thermo-compressive bonding, reactive bonding and/or the like. After two semiconductor wafers are bonded together, the interface between two semiconductor wafers may provide an electrically conductive path between the stacked semiconductor wafers in some applications.
One advantageous feature of stacked semiconductor devices is that much higher density can be achieved by employing stacked semiconductor devices. Furthermore, stacked semiconductor devices can achieve smaller form factors, improved cost-effectiveness, increased performance, and lower power consumption.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.